Airborne Geophysical Investigation beneath Antarctica's Ross Ice Shelf

The Ross Ice Shelf controls the flow of ice into the ocean from catchments consisting of both the East and West Antarctic Ice Sheets. These catchments hold a volume of ice equivalent to ∼12 m of global sea level rise. To adequately understand how this ice will respond to a warming world requires knowledge of the properties and parameters which influence how the ice sheet behaves. These boundary conditions include fundamental knowledge of the Earth, such as the shape of the bed beneath the ice, the seafloor, and the geologic structures of the upper crust. Knowledge of the physiography and sub-surface geology is severely lacking beneath ice shelves due to their inaccessibility.

Here, we use airborne geophysical data from an extensive survey over the Ross Ice Shelf to better understand these boundary conditions. From the analysis of airborne magnetics data, we model the thickness of sediment, the shape of the crystalline basement, and the likely locations of faults throughout the crust under the Ross Ice Shelf. We find a continuous drape of sediment over the seafloor, including deep and narrow fault-bound sedimentary basins beneath the Siple Coast.

Using airborne gravity data, and distributed seismic constraints over the ice shelf, we develop and implement a gravity inversion to recover a higher-resolution bathymetry model beneath the ice shelf. This bathymetry model and our quantification of spatial uncertainty highlight locations likely important for sub-ice shelf ocean circulation and possible recent pinning points. In the process of these geophysical investigations, we reveal a wide range of insights relating to how bathymetry and geology play a critical role in the past, present, and future dynamics of the ice sheet, and how this region has developed over its tectonic history.